A close encounter of the AutoNav kind!

On July 29, 1999, the Deep Space 1 spacecraft came closer to an asteroid than any spacecraft has ever done before or since.

Asteroid Braille was 188 million kilometers (117 million miles) from Earth when Deep Space 1 zipped past it at a distance of only 26 kilometers (about 15 miles). This is the closest any spacecraft has ever come to a solar system body without actually landing on it.

What's more, the spacecraft was going 35,000 miles per hour at the time! This speed is 50 times faster than a commercial jet and twice as fast as the Space Shuttle!

What an amazing feat of navigation! What's more amazing is that the spacecraft piloted itself!

How did DS1 do it?

The spacecraft used a new technology called "AutoNav," or Autonomous Navigation. DS1 took pictures of known asteroids, with the stars in the background. It could recognize the star patterns and figure out exactly where it was. Then it automatically corrected its course using its propulsion system to reach its destination.

By the time the spacecraft reached its target, it had flown about 650 million kilometers (about 400 million miles). To be this accurate, a soccer player would have to kick a ball on Earth and score a goal on the Moon!

The primary mission of Deep Space 1 is to test out new technologies in space.

You can find out more about Deep Space 1 and asteroid Braille at these other Space Place pages: